Improvements in or relating to an actuating mechanism for the feed dog of a sewing machine with free work-arm

摘要

683,292. Sewing-machines.MEFINA SOC. ANON. Dec. 15, 1949 [Dec. 20, 1948], No. 32198/49. Class 112. Feed by dogs.-Feed-bar mechanism for a sewing-machine with a free work-arm comprises a single actuating member (a cam 2 on a rotary shaft 3 in the embodiment shown) connected to the feed-dog bar 7 through a rigid lever 5 rocking about a vertical axis 12 and an elastic lever 27 rocking about a horizontal axis 32; the two levers together form a deformable parallelogram. In the form shown the elastic lever 27 is the feed-lift lever, and is connected to the feedbar 7 by a pin on the latter engaging a slot in the end of the lever, the elasticity of the lever enabling it to follow the feeding movements of the feed-bar. The lever 27 and the part 36 of it which engages the pivot 32 are fixed to a rigid member 28 carrying a member 30 engaging the cam 2 under the pressure of a spring surrounding a slotted pin 39 in which the member 30 is guided; the latter member is pivoted on the lower arm of the member 28 and adjustably secured to its upper arm. The lever 5, which slidably receives a pin 6 on the feed-bar, has adjustably fixed to it an arm 10 with guides 15, 16 slidably receiving a rod 17 carrying a member 18 which has a seating 21 engaging the cam 2, under the action of a spring 22, and a member 25 sliding in an angularly-adjustable guide member 26 by which the feed-stroke is adjusted and reversed. The high and low parts of the cam are concentric with the shaft 3 to give a substantially rectilinear four-motion action. Specifications 683,291 and 683,294 are referred to.